At present, there is neither standard test procedure nor standard methodology for assessment of toughness of thin films. However, researchers have long been trying to make such measurements, thus a spectrum of test methods have been developed, mostly each in its own way. As qualitative or semiquantitative assessment, a simple plasticity measurement or scratch adhesion test can mostly suffice. For quantitative description, however, a choice of bending, buckling, indentation, scratching, or tensile test has to be made. These testing methods are either stress-based or energy-based. This paper gives a critical review on these methods and concludes that, for thin films, the energy-based approach, especially the one independent of substrate, is more advantageous.